// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "net/spdy/spdy_buffer.h"

#include <cstring>
#include <utility>

#include "base/callback.h"
#include "base/logging.h"
#include "base/macros.h"
#include "net/base/io_buffer.h"
#include "net/spdy/spdy_protocol.h"

namespace net {

namespace {

    // Bound on largest frame any SPDY version has allowed.
    const size_t kMaxSpdyFrameSize = 0x00ffffff;

    // Makes a SpdySerializedFrame with |size| bytes of data copied from |data|.
    // |data| must be non-NULL and |size| must be positive.
    std::unique_ptr<SpdySerializedFrame> MakeSpdySerializedFrame(const char* data,
        size_t size)
    {
        DCHECK(data);
        CHECK_GT(size, 0u);
        CHECK_LE(size, kMaxSpdyFrameSize);
        std::unique_ptr<char[]> frame_data(new char[size]);
        std::memcpy(frame_data.get(), data, size);
        std::unique_ptr<SpdySerializedFrame> frame(new SpdySerializedFrame(
            frame_data.release(), size, true /* owns_buffer */));
        return frame;
    }

} // namespace

// This class is an IOBuffer implementation that simply holds a
// reference to a SharedFrame object and a fixed offset. Used by
// SpdyBuffer::GetIOBufferForRemainingData().
class SpdyBuffer::SharedFrameIOBuffer : public IOBuffer {
public:
    SharedFrameIOBuffer(const scoped_refptr<SharedFrame>& shared_frame,
        size_t offset)
        : IOBuffer(shared_frame->data->data() + offset)
        , shared_frame_(shared_frame)
    {
    }

private:
    ~SharedFrameIOBuffer() override
    {
        // Prevent ~IOBuffer() from trying to delete |data_|.
        data_ = NULL;
    }

    const scoped_refptr<SharedFrame> shared_frame_;

    DISALLOW_COPY_AND_ASSIGN(SharedFrameIOBuffer);
};

SpdyBuffer::SpdyBuffer(std::unique_ptr<SpdySerializedFrame> frame)
    : shared_frame_(new SharedFrame())
    , offset_(0)
{
    shared_frame_->data = std::move(frame);
}

// The given data may not be strictly a SPDY frame; we (ab)use
// |frame_| just as a container.
SpdyBuffer::SpdyBuffer(const char* data, size_t size)
    : shared_frame_(new SharedFrame())
    , offset_(0)
{
    CHECK_GT(size, 0u);
    CHECK_LE(size, kMaxSpdyFrameSize);
    shared_frame_->data = MakeSpdySerializedFrame(data, size);
}

SpdyBuffer::~SpdyBuffer()
{
    if (GetRemainingSize() > 0)
        ConsumeHelper(GetRemainingSize(), DISCARD);
}

const char* SpdyBuffer::GetRemainingData() const
{
    return shared_frame_->data->data() + offset_;
}

size_t SpdyBuffer::GetRemainingSize() const
{
    return shared_frame_->data->size() - offset_;
}

void SpdyBuffer::AddConsumeCallback(const ConsumeCallback& consume_callback)
{
    consume_callbacks_.push_back(consume_callback);
}

void SpdyBuffer::Consume(size_t consume_size)
{
    ConsumeHelper(consume_size, CONSUME);
};

IOBuffer* SpdyBuffer::GetIOBufferForRemainingData()
{
    return new SharedFrameIOBuffer(shared_frame_, offset_);
}

void SpdyBuffer::ConsumeHelper(size_t consume_size,
    ConsumeSource consume_source)
{
    DCHECK_GE(consume_size, 1u);
    DCHECK_LE(consume_size, GetRemainingSize());
    offset_ += consume_size;
    for (std::vector<ConsumeCallback>::const_iterator it = consume_callbacks_.begin(); it != consume_callbacks_.end(); ++it) {
        it->Run(consume_size, consume_source);
    }
};

} // namespace net
